Crankcase ventilation



Sept. 7, 1954 w. E. BRILL 2,683,316

CRANKCASE VENTILATION Filed Nov. 1, 1946 3nventor Gttornegs PatentedSept. 7, i954 2,688,316 CRANKCASE VENTILATION William E. Brill,Cleveland, Ohio, assignor to I General Motors Corporation, Detroit,Mich., a

corporation of Delaware Application November 1, 1946, Serial No. 707,076

4 Claims.

The present invention relates to crankcase ventilating and oilseparating systems for engines.

In conventional systems of this type in order to prevent pickup of theoil separated in the separator when crankcase vapors are, drawntherethrough by connection with an engine suction source-la U-shaped oilreturn line is connected between the separator and crankcase ofsufficient height to act as a U-tube seal for maximum values of enginesuction.

In installations on submarines where a telescopic engine air intake pipeis required to permit operation of the engines at different submergeddepths it has been found that the resistance to air now through theintake pipe and numerous bends in the connections to the engine thatthere is not suflicient height in the hull of the submarine for a U-tubeseal for this purpose.

The principal object of the invention is to provide a crankcaseventilating system including means connected between the crankcase and avariable lower pressure or suction source for separating the lubricantfrom the vapor drawn from the crankcase and insuring that all of thelubricant separated is returned to the crankcase irrespective of widevariations in suction of the source.

The means by which this object is accomplished is described in detail inthe following specification and one modification is illustrated in theaccompanying drawing.

Figure 1 is a partial side elevation view of one end of an internalcombustion engine incorporating my crankcase ventilating system withparts broken away. 1

Figure 2 is an enlarged end elevation view of details shown in Figure 1with parts shown broken away and in section.

As best shown in Figure l the engine comprises a crankcase l andcylinders 3 in which pistons therein are connected by connecting rods tothe crankshaft, not shown, in conventional manner to cause rotationthereof in conventional manner. The engine illustrated is provided witha scavenging blower operatively connected to the engine crankshaft andlocated in a blower housing 5 secured on one end of the enginecrankcase. A telescopic engine air inlet pipe is shown generally at 1connected to the inlet side of the blower housing 5 and the suctiontherein is proportional to the resistance to air flow therethroughdepending on its length and number of bends therein and alsoproportional to the speed of the engine driven blower. The outlet of theblower housing 5 is connected by suitable passages, not shown, in theengine crankcase l to well known type is secured to the blower housingand connected by a suction outlet pipe 13 to the suction side of theblower and a vapor inlet pipe 15 is connected between the crankcase Iand the separator. The oil separated by the separator is led by an oilreturn line including pipe I! between the separator l I and the inlet ofan oil scavenging pump IQ of the constant displacement gear type securedto the crankcase and driven by the engine. The outlet of the oilscavenging pump I9 is connected by oil delivery return pipe 2| ofU-shape to the crankcase I. One end of the U-shaped pipe 2| is shown inFigures 1 and 2 connected to the crankcase at a point slightly above thelevel of the other end of the pipe 2|, shown connected to the pumpoutlet, so that some oil is always retained in the housing of the pumpl9 whereby an oil film seal is continuously maintained between the pumphousing and gears to prevent oil from the tube 2! and in the separatorentering the separator suction pipe I3 and the engine blower andcylinders and thus insuring that all the oil from the separator isreturned by the pump I9 through the return pipes I! and 2| to thecrankcase, irrespective of the degree of suction in the separator andair inlet pipe of the engine connected to the inlet or suction side ofthe blowers. This operation makes the above described crankcaseventilating and oil separating system suitable for use in engines wherewide and sudden changes in suction are applied to the separator due tochanges in the engine speed or variations in the restriction to air flowin the suction passages.

I claim:

1. In a crankcase ventilating and oil separating system, a crankcase, asource of variable suction, an oil separator connected between saidcrankcase and variable suction source for separating oil from the vapordrawn from said crankcase and through said separator, an oil returnconnection connected between said separator and said crankcase andincluding a positive displacement oil scavenging pump, the outlet ofsaid pump being positioned in said oil return connection at a levelbelow the point of connection to said crankcase so that some oil isretained in the pump at all times.

2. In combination, an engine having a cylinder, a crankcase and an airinlet pipe for said cylinder, an oil separator connected between the inserve as an oil seal against the suction-in said air intake pipe.

3. In combination, an engine-having a crankcase, a blower driven by saidengine 'forsupply ing air to said engine, an air inlet pipe connected tothe inlet of said blower, an .oilscavenging pump driven by said engine,an oil separator connected between said inlet pipe and said-crankcasefor separating oil from the vapor from said crankcase, and anoil-returnzconnection including. said; scavenging, pump connectedbetween said separator and crankcase to return separated oil tosaidcrankcase, the pump outlet being-lo cated at a lowerlevel in saidoil return 00111160- tion than its pointofconnection tosaidcrank- 4 casein order to retain some oil in said pump at all times to seal saidreturn connection against the suction in said inlet pipe.

4. In combination, an engine, a blower driven by said engine andsupplying air under pressure to said engine, a telescopic air inlet pipeconnected to the inlet of said blower, an oil separator connectedbetween said blower inlet and said crankcase, and a combined oil returnline and suction seal connected between said separator and said enginecrankcase and including a positive. displacement engine driven oilscavenging pump, said oil return line between the outlet of said pumpand said crankcase being of U -shape and having one end connected tosaid crankcase at a higher level than the other end connected tothe.outletof said pump to retain some separated oil in the pump outlet atall times.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,236,187 hemp Aug. 7, 1917 1,484,607 Hunt Feb. 19, 19241,623,242 Gruber Apr. 5, 1927

